Is there a way to tell how many hours the machine has run?
There are (five) NC time counters. Maybe on "check data" screen for this OSP. For newer OSP's NC counters are under user parameters.
It doesn't tells about machine condition however. You check work accuracy. Simple cut small diameter and bigger, let's say 3mm and 30mm. Check the diameter error difference, check roundness ...
Some machine tools from that period were equipped with mercury timer. Maybe You will find in control cabinet or maybe display visible outside.